At the time it was first developed, heroin seemed like such a good idea. So did the lobotomy, a surgical procedure whose inventor won a Nobel Prize.

When Rachel Carson's Silent Spring revealed the evils of the pesticide DDT, banning it seemed like an excellent idea.

But all were eventually proven to have horrible unintended consequences.

They are among Seven Stories of Science Gone Wrong, the subtitle of Pandora’s Lab, a new book by Paul A. Offit, a pediatrician who specializes in vaccines and infectious diseases. He holds numerous positions at the University of Pennsylvania’s Perelman School of Medicine and the Children’s Hospital of Philadelphia, where he is director of the Vaccine Education Center.

He spoke to us recently about his book, and why — especially at a time when facts are under fire — science matters more than ever. (The four other mistakes? Margarine, which has been shown to increase, not reduce, the risk of heart disease. Eugenics, which led to the forced sterilization of millions of Americans and the slaughter of millions of Jews in Germany. Linus Pauling’s advice to take megadoses of Vitamin C, which Offit says does not prevent or cure the common cold, but can cause other severe health problems. And synthetic nitrogen, which has fertilized enough food to feed billions, but also caused algae blooms that choke our waterways and spawned the invention of mustard gas and chlorine gas weapons.)

Let’s start with lobotomies, which have a Philadelphia connection. What on earth were people thinking?The first lobotomy was by Egas Moniz, a Portuguese neurologist, in 1935, for which he won the Nobel Prize in 1949. The New York Times declared him a brave explorer of the human mind. The prestigious New England Journal of Medicine thought this was a rational approach. It was embraced by the medical establishment. Actually, it was a therapy of despair. We didn’t really have a treatment for schizophrenia. We had institutions for the mentally disabled, and they were bursting at the seams.

The real champion of the procedure was Walter Freeman, who performed 7,000 lobotomies in the U.S. He invented the ice-pick lobotomy. In his hands, it became a six-minute outpatient procedure with no anesthesia and no sterilization. He was from Philadelphia. Grew up at 18th and Spruce, just off Rittenhouse Square. He went to Episcopal and to Penn’s School of Medicine. And he trained at what was then Philadelphia General Hospital. He was respected. He did his first lobotomy in the late 1930s. He did his last in 1970, at which point he was a pariah.

Lobotomies were sold as a cure-all. But they didn’t always work. Rosemary Kennedy, who was only mildly developmentally disabled, had one and spent the rest of her life in an institution. What we finally realized is that the procedure could cause cerebral hemorrhage and death. It could cause permanent seizure disorder. It rendered you like a zombie, which when you were trying to house thousands and thousands of people in a mental institution and some were aggressive, was perceived as of value. But it was incredibly cruel.

Heroin seemed like great painkiller. How did we get it so wrong?The point in the heroin chapter is that you can blame the current opioid epidemic, one that kills tens of thousands of people a year in the U.S., on medical hubris. If you had to lay the blame of this epidemic on anyone, it would be at the feet of doctors and scientists who have believed, wrongly, for 2,500 years that they can separate pain relief from addiction.

Humankind’s first pain medicine was opium. Opium users became opium addicts. To solve that problem, we decided to purify the main ingredient. So opium addicts became morphine addicts. Then we decided to chemically modify morphine so it would cross the blood-brain barrier more efficiently — and thus require less of the chemical for the same effect. Morphine addicts became heroin addicts. Then we thought if we could just take another component of morphine and, again, chemically modify it to make oxycodone, that we could separate pain relief from addiction. Again, it didn’t work.

When we believed that no one should suffer a moment of pain, and became very quick to prescribe opioids, we created the opioid epidemic.

Conversely, DDT was vilified. It was banned. Why wasn’t that a good thing?That was the hardest chapter to write. Rachel Carson, whose book Silent Spring led to the banning of DDT, was a brave woman. She was a hero. She stood and up and said, “I think we’re affecting our environment.” She was a great writer, really smart. I have such respect for what she did.

What I’m trying to say is that she wasn’t exactly right about DDT. She overstated it. When you’re as powerful a writer as she is, I don’t think you can say that DDT causes children to suddenly die. She scared people disproportionately. And while she was right that DDT should have been eliminated for agricultural use, it shouldn’t have been discontinued for public health use. Tens of millions of children have died from malaria. The proof is in the pudding. DDT was reinstated by the World Health Organization in 2006.

Is there anything that’s widely accepted now, but that you think may ultimately be proven wrong?Our reliance on the Prostate-Specific Antigen test — or PSA test — as a way to screen for prostate cancer probably has caused a lot of unnecessary radiation and surgery for men. All to cure a disease that was unlikely to kill them. That also applies to screening tests for thyroid cancer and breast cancer. I think we’ll get better at defining cancer. Cancer used to be the thing that would kill you. That’s no longer true. Most men die with prostate cancer, not from it.

With e-cigarettes, time will tell. Public health officials contend that this could be a gateway drug to cigarette smoking. But the fact remains that, with e-cigarettes, you’re vaporizing a liquid, you’re not burning a leaf. Therefore, you’re not creating the kinds of tars that cause lung cancer. So the question becomes: Do e-cigarettes replace cigarettes? If they do, that has to be an advantage. There’s been an inverse relationship with the introduction of e-cigarettes and lung cancer. The question is whether that’s coincidental or causal.

GMOs — genetically modified organisms — are a heated issue. They shouldn’t be. Essentially, no one has been harmed by GMOs. We’ve been genetically modifying things since we first started farming and raising animals. Farmers have been selecting for certain mutations for thousands of years. I’m arguing there’s no difference between a farmer selecting a mutation and a scientist creating a mutation.

Science seems to be experiencing a crisis of confidence just now. Consider that the head of the U.S. Environmental Protection Agency disputes climate change. Why should we still believe in science?At some level, the subtitle of the book is a little misleading. Scientists can mislead us. Science ultimately gets it right. There’s a lot of bad science that’s not only published, but also rewarded. Moniz wins the Nobel Prize for his invention of lobotomy. That didn’t stand the test of time. Ancel Keys claims that fat is bad for us and drives us out of the arms of butter and into margarine. His finding wasn’t reproducible. Scientist after scientist found that trans fats are harmful.

People want to know things, especially with regard to their health. We’re going to know more 100 years from now than we know now, and that’s unsettling. In part, that’s what makes people who are certain, who are immutable, so attractive. Science is questioning and challenging and engaging. But for some people, they like the guru. The attraction is that they act as if they know everything you need to know. But you should never trust the person; you should always trust the process.

One can reasonably be skeptical of scientists, but it’s not reasonable to be skeptical of science, which stands on the firm pillar of reproducibility. Truths emerge over time, and consensus emerges over time. If you’re right, you’ll be proven to be right. And if you’re wrong, there’s no hiding.